The KardashiansThreatened With LawsuitOver Cheap Trick

10/29/2012 5:15 AM PDT

The Kardashians have been accused of a cheap cover-up, stealing the name of a high-end make-up line and slapping it on their own drugstore brand ... so claims the dude who sells the fancy products.

Kim, Khloe and Kourtney are launching Khroma Beauty ... a cosmetics line you can get next month at not-so-fancy places like CVS, Sears, and Ulta.

Michael Rey, the co-owner of Chroma Makeup in Bev Hills tells TMZ ... his brand took 12 years of blood, sweat and tears to build and now boasts an A-List clientele -- but he grouses the Kardashians line cheapens his products and creates confusion in the marketplace.

Michael fears his high-end customers will run for other parts of the Hills ... thinking their primo cosmetics are not so primo after all ... and they'll be embarrassed to say they wear Chroma.

Michael says he's hired a legal team, but hasn't made contact with the Kardashians just yet. He hopes they'll change the name -- but if they don't he's prepared to take legal action.

Michael has drafted a letter to his customers making it as clear as concealer -- Chroma in NO WAY is associated with the "low-budget cosmetic products" the Kardashians are hocking.